Why don't humans need a caecum?

Humans do not need a caecum because our diet has evolved to include a wide variety of easily digestible foods, reducing the necessity for the fermentation of plant material that the caecum facilitates in some herbivorous animals. While the caecum plays a role in gut health and the immune system, humans can maintain digestive health without it. Additionally, the appendix, a vestigial structure in humans, may still provide some immune functions, indicating that while the caecum is less critical, some related structures may retain some utility.